By Alastair Macdonald and Jan Strupczewski
Belgian police have captured a suspect reportedly carrying a suitcase full of explosives, after shooting him in the leg during a police operation following the suicide bombings in Brussels.
The federal prosecutor's office said the arrest was one of three in Brussels on Friday linked to the arrest in Paris on Thursday of an Islamist convicted in Belgium last year and suspected of plotting a new attack.
Nine people in total have been arrested since Thursday in Belgium and two in Germany, as European authorities swoop on militants believe linked to the Brussels attacks that killed 31 people and to attacks in Paris last November that killed 130.
Heavily armed police and troops cordoned off an area around an intersection in the Brussels borough of Schaerbeek. Three blasts were heard, which local mayor Bernard Clerfayt said were controlled explosions.
Belgian public broadcaster RTBF quoted Clerfayt as saying the suspect was detained after being wounded and that he was linked to Tuesday's suicide bombings in Brussels. It said he had been found to be in possession of a suitcase full of explosives.
Witnesses told local media police had shot the man in the leg at a tram stop after he failed to respond to their orders.
"I heard two explosions, they were shooting. I opened the window and saw a man lying near the tram stop. The police ordered him to show his hands, remove his jacket. They said that if he did not comply, they would use their weapons," a witness told La Libre newspaper.
Video from the scene showed the man lying on his side as a bomb squad robot approached him, checking for explosives.
Islamic State suicide bombers hit Brussels airport and a metro train on Tuesday in attacks investigators believe were carried out by the same cell responsible for November's attacks in Paris.
The Belgian federal prosecutor's office said six people were held in Brussels on Thursday, of whom three were released and three remanded in custody.
Three others were detained on Friday following the arrest in France of Reda Kriket, a 34-year-old Frenchman sentenced to 10 years in Brussels in absentia in July as part of an Islamist recruiting network dubbed the Syrian Connection.
Interior Minister Bernard Cazeneuve said Kriket's arrest helped "foil a plot in France that was at an advanced stage".
A police source said investigators found acetone peroxide explosives in an apartment in a Paris suburb after the arrest.
Germany's Der Spiegel magazine said German police had arrested two people, one of whom had received phone messages with the name of the metro station bomber and the word "fin" - French for "end" - three minutes before the metro blast.
US Secretary of State John Kerry arrived in Brussels on Friday to offer assistance in security. Two of the Brussels victims were Americans.
"The United States is praying and grieving with you for the loved ones of those cruelly taken from us, including Americans, and for the many who were injured in these despicable attacks," Kerry said after meeting Prime Minister Charles Michel.
Michel rejected resignations offered by his interior and justice ministers on Thursday over a failure to track one of the airport bombers, Brahim El Bakraoui, 29, who had been expelled last year by Turkey as a suspected fighter.
Bakraoui's brother Khalid, 26, was the bomber who struck Maelbeek metro station.
Prosecutors confirmed the second airport bomber was Najim Laachraoui, a veteran Belgian Islamist fighter in Syria suspected of making explosive belts for November's Paris attacks.